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Best insulation knife UK: one name per job

Updated: October 2026

You want one name, not a six-row table, before you climb into a glass-wool loft or unwrap foil-faced board. The best insulation knife UK answer in this set is a job plus a review count, not a 5.0 from six ratings. Every attribute and the 19 October 2026 amazon.co.uk prices stay in the [insulation knife comparison](/hub/cutting-tools/insulation-knife). This page names the top pick, who should skip it, and the cheaper fibre saw. Edge order without a crown sits on the [insulation knife buying guide](/hub/cutting-tools/insulation-knife/sub/insulation-knife-buying-guide). Peter F. wrote this for DIY & tools. A qualifying purchase can earn a commission at no extra cost to you.

You want one name, not a six-row table, before you climb into a glass-wool loft or unwrap foil-faced board. The best insulation knife UK answer in this set is a job plus a review count, not a 5.0 from six ratings.

Our top picks

Everhard Everhard MK46000 insulation knife

Best overall

Everhard Everhard MK46000 insulation knife
7.4/10about £19.01
View offer
Spear & Jackson Spear & Jackson B98INS Predator insulation saw

Best value

Spear & Jackson Spear & Jackson B98INS Predator insulation saw
8.4/10about £11.48
View offer
Bahco Bahco PC-22-INS insulation saw

Rank 3

Bahco Bahco PC-22-INS insulation saw
8.8/10about £15.92
View offer
On this page
  1. 1.The criterion, then the Bahco
  2. 2.Best value for fibre rolls
  3. 3.Skip these if the job does not match
  4. 4.One listing after the material

The criterion, then the Bahco

The criterion is a blade whose length you can check, a job the reviews actually describe, and enough amazon.co.uk texts to see a pattern. On that test the top pick is the Bahco PC-22-INS, £15.92, 4.1 from 540 reviews, a 550 mm waved saw listed at 400 g. That is not a UK-wide award and it is not a laboratory result. It is the long wave saw in this folder with hundreds of UK reviews, against Trade 4 You listings that share six ratings. UK buyers describe a clean cut on 50 mm Kingspan and on mineral-wool slabs when the edge is sharp, with less dust than a wood saw. At 90–150 mm PIR the thin blade binds or wanders. Wickes and PrimeTools cap EPS and XPS at 75 mm. Six shared ratings do not beat 540 reviews.

Best value for fibre rolls

The best value in this set is the Spear & Jackson B98INS Predator at £11.48, 4.2 from 122 reviews, listed at 349 g. That is the cheaper carbon-steel saw for glass-fibre loft roll and rock wool, not a second top pick for thick foil board. UK reviewers cut quilt with less tearing and less fibre cloud than a toothed saw if they keep the strokes short. The length is a conflict, not an average. The amazon.co.uk listing says 350 mm (14 in). Spear & Jackson’s own page states a 270 mm toothless blade and 442 mm overall. A 270 mm blade is only just a through-cut on the usual loft depth. Skip the Predator for thick Kingspan. One UK review calls it useless on that board. Foil facing blunts the edge quickly, and it sticks in fire batt. Those limits still leave it the best value when the job is fibre and the budget is about £11–£12. If you need a 550 mm wave for mixed wool and thinner foam, stay with the Bahco.
Everhard Everhard MK46000 insulation knife

Testsieger

Everhard Everhard MK46000 insulation knife
7.4/10about £19.01
View offer

Skip these if the job does not match

The Everhard MK46000 at £19.01 is a short fixed roofing knife, 3-5/8 in in the bullets. The amazon.co.uk star line is 4.7 from 371. The texts in the file are marked as reviewed in the United States, on polyiso and about 2 in foil-faced foam. That is not a UK loft-roll sample. Included components say sheath; those US texts say cardboard or nothing. Buy it only if you are trimming ISO board and you accept American written evidence. The Trade 4 You YHSC single at £11.95 and the two-pack at £18.50 share a 5.0 from 6 and the same four texts. One text describes a three-pack. A scabbard is listed, which the Bahco wave saw does not offer. That is a reason to look if you want a cover. It is not a reason to call six shared ratings a winner. The Bahco 396-INS at £19.99 is 4.0 from 15 with two texts. It is a pocket wool saw, not a 550 mm replacement.

One listing after the material

If the job is glass-wool roll or rock wool, the Predator at £11.48 is the best value. If you want the 550 mm wave saw with 540 UK reviews for slabs and PIR around 50–70 mm, the Bahco PC-22-INS at £15.92 is the top pick. If the sheet is 100 mm Kingspan, keep a fine-tooth wood saw for the long square cut. A 5.0 from six shared ratings is not the job.

Common questions

Is the Bahco the one for 100 mm Kingspan?
No. Wickes and PrimeTools cap EPS and XPS at 75 mm on the PC-22-INS. UK reviews of that saw are mixed at 90–150 mm, where the blade binds or wanders. Keep a fine-tooth wood saw for the long square cut. The Predator has a Kingspan complaint in its UK file.
Why not the 5.0 saw?
The Trade 4 You YHSC pair is 5.0 from six ratings. Those ratings, the best-seller rank and the four texts are shared across the single and the two-pack, and one text describes a three-pack. That is too thin to crown. A scabbard in the listing is useful; the star line is not a test.
Is the Everhard the best because it has 4.7?
The 4.7 from 371 is the amazon.co.uk listing line. The written reviews in the file are from the United States and describe roofing polyiso. The blade is 3-5/8 in. That is a trimmer, not a loft saw, and those texts are not UK opinion.
What is the cheaper pick if I only cut fibre rolls?
The Spear & Jackson B98INS at £11.48, 4.2 from 122. It is the best value in this set for glass wool and rock wool. Skip it for thick foil-faced board and for fire batt. The length conflict (listing 350 mm, maker 270 mm) stays on the page; do not average it.
Should I buy the two-pack?
Only if you already accept the YHSC as a thin-sample serrated saw and want a spare. The two-pack is £18.50 and uses the same six ratings as the £11.95 single. It does not add a second test. For wool with a real review file, the Predator or the long Bahco is the clearer buy.

Related pages

How to cut Kingspan

Cut rock wool without dust

Insulation knife

Insulation knife buying guide: edge, length, sheath

How to cut insulation board: mark, guide, short cut

Sources

Public UK sources from the research digest. Listing prices, stars and review counts are the amazon.co.uk lines used for this comparison, checked on 19 October 2026.

  1. GOV.UK — Buying and carrying knives (retrieved 19 October 2026)
  2. Criminal Justice Act 1988, section 141A (retrieved 19 October 2026)
  3. ROCKWOOL UK mineral wool safety data sheet (retrieved 19 October 2026)
  4. FEF mineral wool health and safety factsheet (retrieved 19 October 2026)
  5. PrimeTools — Bahco PC-22-INS insulation saw (retrieved 19 October 2026)
  6. Spear & Jackson — Predator insulation saw B98INS (retrieved 19 October 2026)
  7. Centre for Sustainable Energy — loft insulation (retrieved 19 October 2026)
  8. GOV.UK — Approved Document L 2026 (retrieved 19 October 2026)